LEON3 Clock and Timer Driver

Sebastian Huber sebastian.huber at embedded-brains.de
Wed Feb 12 13:33:23 UTC 2014

On 2014-02-12 12:11, Daniel Hellstrom wrote:
> I'm not familiar with this, but indeed it look a bit wrong. The timer resources
> on LEON is not per-CPU, they area shared and we never know how many timers are
> available. Most systems have at least two timers. In case of a multi-processor
> system the LEON3 usually configured which timer it takes by looking at the CPU
> index. It seems like there are two ways, of course the preferable way would be
> to look at LEON3_Cpu_Index in case the AMP CPUs does not involve CPU0. How does
> other AMP systems assign resources? I guess it would be better to solve it in
> another way, by a BSP configuration option instead so select timer? But then
> you would need different kernel libraries...

Ok, I will change this to use LEON3_Cpu_Index instead of 

> Is there a reason why having both timer and ckinit using the same timer?

Its a bit unusual.  On other BSPs this is separate.  Also the timer 
initialization will destroy the setup of the clock driver.

> Perhaps it is assumed that the timer interface is only used when the clock
> timer is disabled?

I don't know.  For the timer driver one dedicated timer should be enough.

With the new CPU counter API we can also use a generic benchmark timer and get 
rid of the problem with the timer driver.

Sebastian Huber, embedded brains GmbH

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